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,'11

Wire-Rope Gearing.

539

It should be noted that horse-power, depending upon pressure
x speed, may be obtained either by a large value of the one or
other quantity. Thus cotton-rope driving depends upon a low
pressure and high speed, but high-pressure driving will now be
considered.

(8.) Wire-Rope Gearing, introduced by Him in 1851, and
called by him ' telo-dynamic transmission,' has since been used in
many long-distance cases, for example :

1.  From turbines to distant mills.

2.  For steam ploughing.

3.  In collieries: both for hauling and raising.

4.  For travelling cranes.

5.  Funicular railways and cable tramways.

6.  Boat towing on canals.

The rope is of steel wire, with hemp or steel core, and six
strands of from 7 to 12 wires each. The wear is more uniform
if the strands twist in the same direction as the rope, as in Lang's
patent. The following table refers to the latter ropes :

Circurnf. of rope.
	Dia. of circle.
	Breaking Stress.
		Dia. of smallest sheave.
	Construction.
	
		Hemp Core.
	Steel Core.
		No. of strands.
	Wires in each strand.

ins.
	ins.
	tons.
	tons.
	ins.
	
	

4
	ij
	34
	51
	24
	6
	12

si
	l
	27
	40
	21
	6
	12

3
	15 TV
	19
	28
	18
	6
	12

2
	JJ
	14
	21
	12
	6
	12

2i
	1
	10
	15
	10
	6
	12

2
	I
	8
	,     12
	10
	6
	12

if
	0
 TV
	6
	9
	8
	6
	10

4
	*
	4*
	H
	6
	6
	8

The wire core does not affect the safety of the rope in bending:
round pullies.

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